GNU bug report logs - #77232
[PATCH] Allow also to get attributes of the terminal line

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Message #26 received at 77232 <at> debbugs.gnu.org (full text, mbox):

From: "Dr. Werner Fink" <werner <at> suse.de>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 77232 <at> debbugs.gnu.org, Philipp Stephani <p.stephani2 <at> gmail.com>
Subject: Re: bug#77232: [PATCH] Allow also to get attributes of the terminal
 line
Date: Mon, 7 Apr 2025 13:51:07 +0200

[Message part 1 (text/plain, inline)]

On 2025/04/05 11:43:40 +0300, Eli Zaretskii wrote:
> Ping! Werner, do you plan on submitting a modified patch?

What is about the attacheds patch ... here I go with the
latest manual page ioctl_tty(2) as well if the macro
MAP_DROPPABLE is not defined then the value 0x08 is
used.

> > From: Philipp Stephani <p.stephani2 <at> gmail.com>
> > Date: Tue, 25 Mar 2025 17:22:22 +0100
> > Cc: Eli Zaretskii <eliz <at> gnu.org>,
> >  77232 <at> debbugs.gnu.org
> > 
> > 
> > 
> > > Am 25.03.2025 um 16:24 schrieb Dr. Werner Fink <werner <at> suse.de>:
> > > 
> > > On 2025/03/25 16:06:39 +0100, Philipp Stephani wrote:
> > >>>> #endif
> > >>>> 
> > >>>> +/* https://github.com/torvalds/linux/commit/9651fcedf7b92d3f7f1ab179e8ab55b85ee10fc1 */
> > >>>> +#ifndef MAP_DROPPABLE
> > >>>> +#define MAP_DROPPABLE 0x0
> > >> 
> > >> Shouldn't this be 0x08? At least that's how it's defined in mman.h.
> > > 
> > > If the kernel does not know (means header does not know) we should not
> > > set an unknown flags as this will fail also (IMHO).
> > > Only if older header files are used in combination with newer kernel
> > > we would see the current behaviour.
> > 
> > The code in question doesn't actually call mmap, it creates a syscall filter that tests whether any unknown flags are set.  Basically
> >   if ((flags & ~known_flags) != 0) abort();
> > So putting something into known_flags that might not be known to the kernel when Emacs is run is harmless.  In fact, it's beneficial for the case where the mman.h that's used when compiling seccomp-filter.c is older than the kernel that will be used to run Emacs.

Werner

-- 
  "Having a smoking section in a restaurant is like having
          a peeing section in a swimming pool." -- Edward Burr

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